Conventional size radiographic image acquisition units are limited in size and unsuitable for imaging elongated body regions such as the full spine or the leg. The largest conventional radiographic film and radiographic computed radiography plates used in chest radiography are 35×43 cm. (14×7 in.). When it is necessary to obtain a radiographic image of a full spine or leg, several approaches have been used. If film/screen technology is used, either an extra long, non-standard radiographic film is used, or as disclosed in U.S. Pat. No. 3,774,045, issued Nov. 20, 1973, inventor Trott and U.S. Pat. No. 3,725,703, issued Apr. 3, 1973, inventor Bucky, cassette or cart is provided for holding a plurality of overlapping conventional sized film cassettes or packs. In the case of a special elongated film, the cost of the film and its processing is substantially greater than the cost of the conventional sized film. In the case of multiple film solutions, the films must be taped together to obtain the full length radiographic image. This introduces overlap and alignment problems.
Similar solutions have been proposed when computed radiography plates are used. Thus, U.S. Pat. No. 5,130,541, issued Jul. 14, 1992, inventor Kawai discloses a self enclosed CR unit using elongated CR plates that are exposed, read, erased and reused within the unit. U.S. Pat. No. 5,111,045 discloses a self enclosed unit using conventional sized CR plates that are exposed, read, erased and reused within the unit. When an elongated body region is imaged, first and second overlapping CR plates are positioned at the exposure station, exposed and then processed. Both of these solutions are disadvantageous in the use of an expensive, heavy, self-enclosed unit that is unsuitable for use when a patient is unable to use the unit due to physical disability or when admitted to a hospital emergency room, intensive care unit or surgical suite.
EP Patent application EPO 919856A1, published Feb. 6, 1999, inventor Dewaile et al. discloses an assembly for recording a radiographic image of an elongated body including a plurality of CR cassettes holding conventional sized CR plates that are held in staggered arrangement so that the length of the staggered arrangement is equal to at least the length of the elongated body. After exposure, the CR plates are read individually and the read electronic images are stitched together to form the entire image of the elongated body. This technique is disadvantageous in requiring the use of a special assembly to hold the CR cassettes. U.S. Pat. No. 5,986,279, issued Nov. 16, 1999, inventor Dewaile, discloses an elongated CR cassette holding a plurality of overlapping or non-overlapping CR screens. After exposure, the CR screens are removed from the elongated cassette, put into “normal” sized cassettes, and applied to a read out device that is able to read out normal sized cassettes. This technique is disadvantageous in the time and expense involved in loading and unloading the elongated cassette as well as in the subsequent handling of individual CR cassettes to enable CR screen readout.
There is thus a need for a solution to these problems.